U.K. researchers have shown how people associate attractiveness with healthy-looking skin.

Researchers from the universities of Bristol and St. Andrews in the United Kingdom have found that the color of a person's skin affects how healthy, and therefore attractive, they appear, and have found that diet may be crucial to achieving the most desirable complexion. The work will be published in the December issue of Springer's International Journal of Primatology.

Using specialist computer software, a total of 54 Caucasian participants of both sexes were asked to manipulate the skin color of male and female Caucasian faces to make them look as healthy as possible. They chose to increase the rosiness, yellowness and brightness of the skin.

"Most previous work on faces has focused on the shape of the face or the texture of the skin, but one of the most variable characteristics of the face is skin color," said Dr. Ian Stephen, who is now at the University of Bristol. "We knew from our previous work that people who have more blood and more oxygen color in their skins looked healthy, and so we decided to see what other colors affect health perceptions. This has given us some clues as to what other skin pigments may relate to a healthy appearance."

Skin that is slightly flushed with blood and full of oxygen suggests a strong heart and lungs, supporting the study's findings that rosier skin appeared healthy. Smokers and people with diabetes or heart disease have fewer blood vessels in their skin, and so skin would appear less rosy.

The preference for more golden, or yellow-toned skin as healthier might be explained by the carotenoid pigments that people get from the fruit and vegetables in their diet. These plant pigments are powerful antioxidants that soak up dangerous compounds produced when the body combats disease. They are also important for our immune and reproductive systems and may help prevent cancer.

They are the same dietary pigments that brightly colored birds and fish use to show off their healthiness and attract mates, and the researchers think that similar biological mechanisms may be at work in humans. "In the West, we often think that sun tanning is the best way to improve the color of your skin," said Stephen, "but our research suggests that living a healthy lifestyle with a good diet might actually be better."

Melanin, the pigment that causes the tan color when skin is exposed to the sun makes the skin darker and more yellow, but participants in the study chose to make skin lighter and more yellow to make it look healthier. "This discovery is very exciting and has given us a promising lead into cues to health," said Professor David Perrett, head of the Perception Lab at the University of St. Andrews, where the research took place. "What we eat and not just how much we eat appears to be important for a healthy appearance. The only natural way in which we can make our skin lighter and more yellow is to eat a more healthy diet high in fruit and vegetables."